Punch-sharpening device



March 18, 1930. sin; TEVANDER i 1,751,113

PUNCH SHARPENI NG DEVICE Filed NOV. 22. 1928 60;)? gander L T I ZI S Jzforrz a};

Patented Mar. 18, 1930 SWAN N. TEVANDER, OF MAYWOOD, ILLINOIS PUNCH-SHARPENING DEVICE Application filed. November 22, 1928; Serial No. 321,251.

The present invention pertains to sharpening tools and more particularly to a tool of the type adapted for sharpening the cutting edges of a punch. An object of the invention is to provide a tool of simple and durable construction for effecting the sharpening operation in a novel and improved manner. A further object is to provide a tool capable of performing the sharpening operation, ac-

curately and expeditiously without removing the punch from the machine. It consists in certain features and elements, in combination, as herein shown and described, and as set forth in the claims.

In the drawings:

Figure 1 is a fragmentary View of a punch and die shown partly in section and in operating relation with a tool embodying the present invention shown in sharpening posi- 2 tion.

Figure 2 is a side view of the hammer and of the tool, with a part of the handle broken away.

Figure 3 is an end view of the hammer.

In the metal punching art it is generally known that after a punch has been in use for a period of time its cutting edges wear dull or become nicked; and the cutting edge nearly always becomes reduced in size. The usual practice heretofore of replacing the cutting edge and restoring it to proper size was effected by hand, and consisted in upsetting the cutting edge by swaging or peening with a special hand hammer and then passing the punch through the die to trim off the wire edge which would represent the excess enlargement produced at the cutting edge by the peening operation. Special skill is required to put a good uniform cutting edge on a punch in this manner and the method is both tedious and inaccurate. It may even necessitate removing the punch from the machine because of the limited space otherwise available for the hammer strokes. This of course results in a considerable loss of time, especially in cases involving an intricate and difficult set-up. V

As shown in Figure 1 of the drawings, the numeral 1 represents a fragmentary portion of a punch of a machine of conventional design having a co-operating die, 2, mounted on a base plate, 3. It will be understood that the punch and die may be of'various shapes or designsto suit the particular requirements. The outer periphery of the lower end, 4, of the punch is the actual cutting edge which taken with its co-operating die perforates the metal by a shearing action.

My improved tool for sharpening the cutting edge of the punch consists of a rotary hammer, 5, of polygonal cross section, hav ing a plurality of flat faces, 6, and as shown the hammer is. hexagonal. Preferably the corners formed by the contiguous fiat faces are chamfered or rounded off as at 7, to obviate possible denting or nicking of the cutting edge, which would be apt to result in the sharpening operation if these corners were sharp. The rotary hammer is of relatively hard material and is fixedly mounted on a rigid terminal shank or shaft, 9,0f a flexible shaft, 10, abutting again'stthe shoulder, 9 of said shank by means of lock nuts, 11, which tend to tighten in a direction such that they hold the hammer more firmly on the shank, when the tool is rotated to perform its work. Of course, if desired, the hammer may be keyed or other means provided forjpositively fixing it to the shank, 9. A stationary handle, 13, in the nature of a sleeve is rigidly secured to the tubularv casing, 14,'for the flexible shaft and also serves to provide journal support for the shank, 9. It will be understood that the flexible shaft is driven from any suitable source of power such as a portable electric motor (not shown).

Thus in the sharpening operation, the handle, l3, provides a convenient grip for the operator in directing the rotary hammer against the cutting edge, l. The rotary hammer is of considerably harder material than the punch, and due to its rapid rotation and the impact of its blunted edges, 7, of the hammer thereagainst serves to upset or swage the cutting edge of the punch very quickly 9 forcing the material to flow outwardly as indicated at 4 in the drawings. 7

Furthermore, by means of this tool, the

upsetting can be effected very uniformly,

even by an unskilled operator, and manifestly more expeditiously than with a hand hammer.

The portability of the tool effects a substantial saving in time, by permitting the performance of the sharpening of the punch without 7 removing it from the machine, thus eliminating resetting and locating the punch in the machine. The construction'is simple, compact and durable, and due to theflexibility of its drive connection, permits it to be used in close quarters, on the cutting edges of punch of fairly complicated design. 7

1. In a tool for the purpose indicated, a rotary member of non-circular cross section, a support adapted for directingsaid member against the cutting edge of a punch or like partand means'for imparting rotary motion to said member independently of its contact l with such part forcausing upsetting of said cutting edge of the part.

2. In atool for the purposeindicated, a rotary. 'member Y of polygonal cross-section, a support for manually directing said member around the cutting edge of a punch or like device, whereby the hammer blows struck by the surfaces of saidmember rotating against thepunch cause upsetting or peenin of the cutting edge of the punch, and means fbr drivin g said rotary element. 7 o a V 3. In a tool as defined in claim 2, the corners formed by the abutting contiguous surfaces being rendered blunt. V p

4. In a tool as defined in claim 2, the outer surface of said rotary member being composed of a plurality of connected relatively flat surfaces disposed parallel to the axis of rotation of j said member, and equidistant therefrom.

5. In a tool as defined 1n claim 2, said means including a flexible drive connection to permit said rotary member to its work.

6. A tool for the purpose set forth, comuniversal'movement of the tool in applying prising incombination, a stationary handle, a

shaft supported in said handle, said shaft having a shoulder abutting against the end of said handle, a rotary member of polygonal cross-section mounted on said shaft on the opposite side of the shoulder and adaptedto operate on the cutting edge of'a punchror the like, for upsetting or swaging said cutting edge, and a flexible drive shaft connected to .said first mentioned shaft.

SWAN; TEVANDER. 

